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package com.nulldev.util.web.HttpServer3.extensions.websocket.util;

import java.io.UnsupportedEncodingException;

/**
 * A class encapsulating the reason why a web socket has been closed, or why it
 * is being asked to close. Note the acceptable uses of codes and reason phrase
 * are defined in more detail by
 * <a href="http://tools.ietf.org/html/rfc6455">RFC 6455</a>.
 *
 * @author dannycoward
 */
public class CloseReason {

	private final CloseReason.CloseCode closeCode;
	private final String reasonPhrase;

	/**
	 * Creates a reason for closing a web socket connection with the given code and
	 * reason phrase.
	 *
	 * @param closeCode    the close code, may not be {@code null}
	 * @param reasonPhrase the reason phrase, may be {@code null}.
	 */
	public CloseReason(CloseReason.CloseCode closeCode, String reasonPhrase) {
		if (closeCode == null) {
			throw new IllegalArgumentException("closeCode cannot be null");
		}

		try {
			if (reasonPhrase != null && reasonPhrase.getBytes("UTF-8").length > 123) {
				throw new IllegalArgumentException("Reason Phrase cannot exceed 123 UTF-8 encoded bytes: " + reasonPhrase);
			}
		} catch (UnsupportedEncodingException uee) {
			throw new IllegalStateException(uee);
		}
		this.closeCode = closeCode;
		this.reasonPhrase = "".equals(reasonPhrase) ? null : reasonPhrase;
	}

	/**
	 * The Close code associated with this CloseReason.
	 *
	 * @return the close code.
	 */
	public CloseReason.CloseCode getCloseCode() {
		return this.closeCode;
	}

	/**
	 * The reason phrase associated with this CloseReason.
	 *
	 * @return the reason phrase. If there is no reason phrase, this returns the
	 *         empty string
	 */
	public String getReasonPhrase() {
		return (this.reasonPhrase == null) ? "" : this.reasonPhrase;
	}

	/**
	 * Converts the CloseReason to a debug-friendly string. The exact format is not
	 * defined by the specification and may change in future releases.
	 *
	 * @return A String representation of this CloseReason
	 */
	public String toString() {
		return (this.reasonPhrase == null) ? "CloseReason[" + this.closeCode.getCode() + "]"
				: "CloseReason[" + this.closeCode.getCode() + "," + reasonPhrase + "]";
	}

	/**
	 * A marker interface for the close codes. This interface may be implemented by
	 * enumerations that contain web socket close codes, for example enumerations
	 * that contain all the in use close codes as of web socket 1.0, or an
	 * enumeration that contains close codes that are currently reserved for special
	 * use by the web socket specification.
	 */
	public interface CloseCode {
		/**
		 * Returns the code number, for example the integer '1000' for normal closure.
		 *
		 * @return the code number
		 */
		int getCode();
	}

	/**
	 * An Enumeration of status codes for a web socket close that are defined in the
	 * specification.
	 */
	public enum CloseCodes implements CloseReason.CloseCode {

		/**
		 * 1000 indicates a normal closure, meaning that the purpose for which the
		 * connection was established has been fulfilled.
		 */
		NORMAL_CLOSURE(1000),
		/**
		 * 1001 indicates that an endpoint is "going away", such as a server going down
		 * or a browser having navigated away from a page.
		 */
		GOING_AWAY(1001),
		/**
		 * 1002 indicates that an endpoint is terminating the connection due to a
		 * protocol error.
		 */
		PROTOCOL_ERROR(1002),
		/**
		 * 1003 indicates that an endpoint is terminating the connection because it has
		 * received a type of data it cannot accept (e.g., an endpoint that understands
		 * only text data MAY send this if it receives a binary message).
		 */
		CANNOT_ACCEPT(1003),
		/**
		 * Reserved. The specific meaning might be defined in the future.
		 */
		RESERVED(1004),
		/**
		 * 1005 is a reserved value and MUST NOT be set as a status code in a Close
		 * control frame by an endpoint. It is designated for use in applications
		 * expecting a status code to indicate that no status code was actually present.
		 */
		NO_STATUS_CODE(1005),
		/**
		 * 1006 is a reserved value and MUST NOT be set as a status code in a Close
		 * control frame by an endpoint. It is designated for use in applications
		 * expecting a status code to indicate that the connection was closed
		 * abnormally, e.g., without sending or receiving a Close control frame.
		 */
		CLOSED_ABNORMALLY(1006),
		/**
		 * 1007 indicates that an endpoint is terminating the connection because it has
		 * received data within a message that was not consistent with the type of the
		 * message (e.g., non-UTF-8 data within a text message).
		 */
		NOT_CONSISTENT(1007),
		/**
		 * 1008 indicates that an endpoint is terminating the connection because it has
		 * received a message that violates its policy. This is a generic status code
		 * that can be returned when there is no other more suitable status code (e.g.,
		 * 1003 or 1009) or if there is a need to hide specific details about the
		 * policy.
		 */
		VIOLATED_POLICY(1008),
		/**
		 * 1009 indicates that an endpoint is terminating the connection because it has
		 * received a message that is too big for it to process.
		 */
		TOO_BIG(1009),
		/**
		 * 1010 indicates that an endpoint (client) is terminating the connection
		 * because it has expected the server to negotiate one or more extension, but
		 * the server didn't return them in the response message of the WebSocket
		 * handshake. The list of extensions that are needed SHOULD appear in the
		 * /reason/ part of the Close frame. Note that this status code is not used by
		 * the server, because it can fail the WebSocket handshake instead.
		 */
		NO_EXTENSION(1010),
		/**
		 * 1011 indicates that a server is terminating the connection because it
		 * encountered an unexpected condition that prevented it from fulfilling the
		 * request.
		 */
		UNEXPECTED_CONDITION(1011),
		/**
		 * 1012 indicates that the service will be restarted.
		 */
		SERVICE_RESTART(1012),
		/**
		 * 1013 indicates that the service is experiencing overload
		 */
		TRY_AGAIN_LATER(1013),
		/**
		 * 1015 is a reserved value and MUST NOT be set as a status code in a Close
		 * control frame by an endpoint. It is designated for use in applications
		 * expecting a status code to indicate that the connection was closed due to a
		 * failure to perform a TLS handshake (e.g., the server certificate can't be
		 * verified).
		 */
		TLS_HANDSHAKE_FAILURE(1015);

		/**
		 * Creates a CloseCode from the given int code number. This method throws an
		 * IllegalArgumentException if the int is not one of the
		 *
		 * @param code the integer code number
		 * @return a new CloseCode with the given code number
		 * @throws IllegalArgumentException if the code is not a valid close code
		 */
		public static CloseReason.CloseCode getCloseCode(final int code) {
			if (code < 1000 || code > 4999) {
				throw new IllegalArgumentException("Invalid code: " + code);
			}
			switch (code) {
				case 1000:
					return CloseReason.CloseCodes.NORMAL_CLOSURE;
				case 1001:
					return CloseReason.CloseCodes.GOING_AWAY;
				case 1002:
					return CloseReason.CloseCodes.PROTOCOL_ERROR;
				case 1003:
					return CloseReason.CloseCodes.CANNOT_ACCEPT;
				case 1004:
					return CloseReason.CloseCodes.RESERVED;
				case 1005:
					return CloseReason.CloseCodes.NO_STATUS_CODE;
				case 1006:
					return CloseReason.CloseCodes.CLOSED_ABNORMALLY;
				case 1007:
					return CloseReason.CloseCodes.NOT_CONSISTENT;
				case 1008:
					return CloseReason.CloseCodes.VIOLATED_POLICY;
				case 1009:
					return CloseReason.CloseCodes.TOO_BIG;
				case 1010:
					return CloseReason.CloseCodes.NO_EXTENSION;
				case 1011:
					return CloseReason.CloseCodes.UNEXPECTED_CONDITION;
				case 1012:
					return CloseReason.CloseCodes.SERVICE_RESTART;
				case 1013:
					return CloseReason.CloseCodes.TRY_AGAIN_LATER;
				case 1015:
					return CloseReason.CloseCodes.TLS_HANDSHAKE_FAILURE;
			}
			return new CloseReason.CloseCode() {
				@Override
				public int getCode() {
					return code;
				}
			};

		}

		CloseCodes(int code) {
			this.code = code;
		}

		/**
		 * Return the code number of this status code.
		 *
		 * @return the code.
		 */
		@Override
		public int getCode() {
			return code;
		}

		private int code;
	}
}